DMS (derma membrane structure) in Foam Creams

ABSTRACT

The invention relates to a foam formulation comprising an emulsion, comprising an oil phase and a water phase, the oil phase comprising at least one membrane-forming substance forming a lamellar membrane in the foam formulation.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to cosmetic and dermatologic foamformulations, particularly foam creams, based on emulsions of especiallythe oil-in-water type, wherein the oil phase comprises at least onemembrane-forming substance forming a lamellar membrane in the foamformulation.

BACKGROUND OF THE INVENTION 1. Emulsions

The term “emulsion” generally relates to heterogeneous systemsconsisting of two liquids that are not miscible or are only miscible toa limited extent which are typically designated as phases. In anemulsion, one of both liquids is dispersed in the other liquid in theform of fine droplets.

In case that the two liquids are water and oil and the oil droplets arefinely dispersed in water, the emulsion is an oil-in-water emulsion (O/Wemulsion, e.g. milk). The basic character of an O/W emulsion is definedby the water. In case of a water-in-oil emulsion (W/O emulsion, e.g.butter), the opposite principle applies wherein the basic character ishere defined by the oil.

In order to obtain a durable dispersion of a liquid in another liquid,emulsions in a conventional sense require the addition of a surfaceactive agent (emulsifier). Emulsifiers have an amphiphilic molecularstructure consisting of a polar (hydrophilic) and a non-polar(lipophilic) part of the molecule which are separated from each other inspace. In simple emulsions, finely dispersed droplets enclosed by anemulsifier shell of the one phase are present in the second phase (waterdroplets in W/O or lipid vesicles in O/W emulsions). Emulsifiers reducethe surface tension between the phases because they are arranged in theboundary surface between the two liquids. They form surface films at theboundary of the oil/water phases which countervails an irreversiblejoining of the droplets. For stabilizing emulsions mixtures ofemulsifiers are often used.

Conventional emulsifiers can be classified depending on theirhydrophilic part of the molecule into ionic (anionic, cationic andamphoteric) and non-ionic ones:

-   -   The best known example of an anionic emulsifier is believed to        be soap which is the conventional name for the water-soluble        sodium or potassium salts of saturated and non-saturated higher        fatty acids.    -   Important members of cationic emulsifiers are the quaternary        ammonium compounds.    -   The hydrophilic part of the molecule of non-ionic emulsifiers        often consists of glycerol, polyglycerol, sorbitans,        carbohydrates or polyoxyethylene glycols, respectively, and is        most often connected to the lipophilic part of the molecule by        means of ester and ether bonds. The latter consists typically of        fatty alcohols, fatty acids or iso-fatty acids.

The term “emulsifier” or “conventional emulsifier” respectively, isknown in the art. Conventional emulsifiers are described, e.g., in thepublications: Pflegekosmetik, 4th edition, WissenschaftlicheVerlagsgesellschaft mbH Stuttgart, pages 151 to 159 and Fiedler Lexikonder Hilfsstoffe, 5th edition, Editio Cantor Verlag, Aulendorf, pages 97to 121.

By variation of the structure and the size of the polar and thenon-polar part of the molecule, lipophilicity and hydrophilicity ofemulsifiers can be modified to a large extent.

The correct choice of emulsifiers is decisive for the stability of anemulsion. In this respect, the characteristics of all compoundscontained in the system need to be considered. For example, in case ofskin care emulsions, polar oil components such as e.g. UV filters maylead to instabilities. Apart from emulsifiers, other stabilizers are,therefore, additionally used, which, e.g., increase the viscosity of theemulsion and/or act as protective colloid.

Emulsions represent an important type of product in the field ofcosmetic and/or dermatologic preparations which is used in differentapplication fields. Therefore, a variety of products—such as lotions andcreams—are available for skin care, especially for relubricating dryskin. The aim of skin care is to compensate for the loss of lipid andwater caused by daily washing. In addition, such skin care productsshould protect from environmental stress—in particular from sun andwind, and should delay skin ageing.

Cosmetic emulsions are also used as deodorants. Such formulations areused for eliminating the adore of the body that is formed when freshsweat that as such is free of odour is decomposed by microorganisms.

Emulsions in the form of cleaning emulsions are also used for cleaningof the skin and skin adnexa. They are most often used for the cleaningof the face and especially for removing decorative cosmetic. Suchcleaning emulsions have the advantage—in contrast to other cleaningpreparations such as soap—to be especially mild on skin since they maycontain in the lipophilic phase nurturing oils and/or non-polar activeagents—such as, e.g., vitamin E.

Since decades, conventional emulsifiers form the basis for thedevelopment of skin care preparations. Emulsifiers were used asadjuvants for the manufacture and especially for stabilizing emulsions.Recently there were references that the use of emulsifiers in skin carepreparations may lead to problems e.g. in case of sensitive skin sinceemulsifiers typically disturb the integrity of the natural skin barrierand, thus, cleaning of the skin may lead to a loss of natural barriercompounds of the skin. The loss of natural barrier compounds may lead toan increased roughness, dry skin, cracking and wear eczema.

Furthermore, the use of emulsifiers normally results in the conversionof lamellar structures of the lipid barrier into vesicular structuressuch as e.g. micelles or mixed micelles. These vesicles “destroy” atleast a part of the barrier layer of the skin, and, therefore, locallyincrease the permeability of the barrier layer membrane. Due to thisopening of the barrier layer of the skin, the loss of water across theskin (TEWL) is at least temporarily increased and simultaneously thecapacity of the skin to bind moisture is decreased. Continuousapplication of skin care preparations having conventional emulsifiersmay even lead to failure of the skin to maintain its protectingfunction.

Emulsifier-free emulsions are a special form of an emulsion. Theseemulsions are free of emulsifiers in a narrower sense, i.e. free ofamphiphilic compounds having a low molecular weight (molecular weight of<5000) that in suitable concentrations form micelles and/or other liquidcrystalline aggregates. The IUPAC defines the term “emulsifier” asfollows: Emulsifiers (i.e. conventional emulsifiers) are surface-activesubstances. They are preferably arranged in the boundary surface betweenoil phase and water phase and, therefore, reduce the surface tension.Even in low concentration, emulsifiers facilitate the formation of anemulsion. In addition, these substances may increase the stability of anemulsion in that they reduce the rate of aggregation and/or coalescence.According to an interdisciplinary consensus of pharmacists,dermatologists and other experts of the Society of Dermatopharmacy(http://www.dermotopics.de/german/ausgabe_1_03_d/emulgatorfrei_1_2003_d.htm),a formulation may be defined as “emulsifier-free” when it is stabilizedby means of surface active macromolecules (having a molecular weight ofover 5000) instead of emulsifiers in a narrower sense (conventionalemulsifiers).

For stabilizing pharmaceutical and cosmetic emulsions, so-called trueemulsifiers are predominantly used, i.e. conventional emulsifiers in thesense of the present description that according to their structure andtheir physical-chemical behaviour belong to the class of tensides. Theyare characterized in an amphiphilic structure and the capability formicelle association. Compounds and mixtures thereof that lead to theformation of a lamellar membrane in the sense of the present inventioninstead of micelle association are, however, not considered asconventional emulsifiers. Examples for such compounds are e.g.phospholipids, such as e.g. lecithins, sphingolipids, ceramides,cholesterol, fatty alcohols, fatty acids as well as there mono- and/ordiesters, as well as sterols, etc., when they are dispersed underspecific conditions as described below. Such mixtures of compounds mayfurther contain triglycerides (not hydrophilic and lipophilic), squalene(not hydrophilic and lipophilic), or squalane (not hydrophilic andlipophilic). Preferred examples for membrane-forming substances of thepresent invention are phospholipids, sphingolipids, ceramides,cholesterol, fatty alcohols, fatty acids as well as their mono- and/ordiesters, and sterols. These compounds, e.g. phospholipids, are notsoluble in water in contrast to typical emulsifiers especially tensideshaving a comparable HLB-value of about 10. Normally, they form nomicelles or hexagonal liquid crystalline phases. Above the phasetransition temperature, they spontaneously form in water exclusivelylarge multilamellar vesicles (LUV). Below the phase transitiontemperature, they can be dispersed in water under high energy input andform lamellar structures. The above-mentioned phase transitiontemperature indicates in this respect the temperature at which agel-like phase is converted into a liquid crystalline phase. Below thephase transition temperature, a gel phase is present, above the phasetransition temperature, a liquid crystalline phase is present. Phasetransition temperatures vary depending on the composition(saturated/non-saturated; short/long) and typically lie, for example, incase of phospholipids between 10° C. and 70° C. For a given system, thephase transition temperature can easily be determined by means of DSC.

Membrane-forming substances also typically contain lipophilic andhydrophilic parts of the molecule. The capacity of a membrane-formingsubstance to form lamellar structures as opposed to micelles depends,however, in particular on the optimal area and/or (boundary surfacecarbon/water), the volume V and the critical chain length l_(c)(Israelachvili, Jacob N.: “Intermolecular and Surface Forces: WithApplications to Colloidal and Biological Systems”. 2^(nd) EditionAcademic Press, London, U K, 1992).

Furthermore, it is in case necessary to select special productionconditions for a system to form lamellar structures. These conditionsare described below regarding the inventive systems in more detail.Although systems in which micellar structures can be converted undersuitable conditions into lamellar structures are known in the art, thereare, however, also systems in which no phase transformation into anotherphase such as e.g. a micellar, hexagonal phase, etc. is possible. Stillother systems allow under suitable conditions for the formation of alamellar phase, however, an alteration of the concentration does notlead to the formation of other mesophases.

Thus, lamellar structures form under well-defined conditions and are notarbitrarily convertible by means of an alteration of the concentrationinto other mesophases such as e.g. micellar structures. In case ofwater-soluble tensides (emulsifiers), micelles, hexagonal and lamellarliquid crystalline phases are formed depending on the tensideconcentration. In this case, it is possible that depending on theconcentration mixtures of different states (hexagonal and lamellar) arepresent side by side in equilibrium. By contrast, membrane-formingsubstances of the present invention are typically not soluble in water.In case of these lipids not soluble in water, such as e.g.phospholipids, liposomal structures are as a rule not present side byside of lamellar structures but either the one structure is present orthe other.

An example of emulsifier-free emulsions are Pickering emulsions.Pickering emulsions are stabilized by means of solids which the finelydivided solid particles stabilize the emulsion so that conventionalemulsifiers may be substantially omitted. In this respect, the solidsaccumulate in the oil/water boundary surface in the form of a layerwhereby the joining of the dispersed phases is prevented. Solidemulsifiers suitable for this purpose are particulate inorganic ororganic solids that are wettable by both lipophilic as well ashydrophilic liquids. In Pickering emulsions, titanium dioxide, tinoxide, silicon dioxide, Fe₂O₃, veegum, bentonit or ethyl cellulose arepreferably used as solids.

However, such solid emulsifiers may also lead to irritations or may evencause allergies in case of sensitive skin.

Cream bases are already used employing a variety of natural or skin-likeingredients, respectively, promising a better skin compatibilityespecially in case of sensitive skin. In this respect, it has been shownthat the use of skin-like ingredients results in an improved skin care.Thus, in these cream bases several components of natural skin lipids,such as e.g. triglycerides are replaced by caprylic acid/caprinic acidtriglycerides (of plant origin), squalene is replaced by squalane (orplant origin), ceramides are replaced by ceramide 3 (of yeast origin),cholesterol is replaced by phytosterols (of plant origin) andphospholipids are replaced by phospholipids (of plant origin).

In this concept, typical adjuvants such as fragrances, colorants,comedogen lipids (e.g. mineral oils), preservatives and criticalemulsifiers are preferably omitted, since these components potentiallyare sensitizing and may lead to irritations of the skin.

These formulations are preferably prepared without conventionalemulsifiers in order to avoid the above-mentioned disadvantages ofconventional emulsifiers.

Without wishing to be bound by a specific theory it is believed that thespecial action of these specifically composed membrane lipids is relatedto the lamellar structure. Omission of conventional emulsifiers preventsthat micelles or vesicles are formed so that the lamellar structure ofthe formed membrane is maintained in the emulsion. This lamellarstructure is based on the (physical) structure and the (chemical)composition of the natural epidermal skin lipids that are preferablypresent as lute substance between the cells (corneocytes) of the stratumcorneum.

Systems based on specifically composed membrane lipids having a lamellarstructure of the membrane are known in the art under the term “DMS®”(Derma Membrane Structure).

3. Foam Formulations

A special application form of cosmetic and/or dermatologic emulsions isthe application as foams. Foam formulations have the advantage that theycan easily be distributed on the skin. The foamy consistency isexperienced as comfortable and the products normally leave a good skinfeeling. In particular, the physical structure of the foam actspositively on the protective action of the skin. Foams are complicatedphysical structures that require a special balance of the componentsconstituting the foam. In general, foams are obtained by spraying aformulation of an emulsion or an aqueous tenside (stabilizer) solution.For example, an emulsion containing propellant is dispensed from apressurized container (such systems are also described in literature andpatent literature as aerosol foams). In this case, the pressurizedmixture of emulsion and propellant expands and forms small foam bubbles.In particular, the dispersed oil phase in which the oil-soluble gas isdissolved expands. However, foams can also be formed by means of othersystems such as, for example, pump sprays.

Upon application, balanced foam formulations have a stable polydispersestructure of two or more phases that forms on the skin a networkstructure that is comparable to a membrane. Such network structures havethe advantage that they develop a protective action, for example againstcontact with water, however, allow for the unhindered gas exchange withthe environment. In such foams, there is practically no obstacle for theperspiratio insensibiles and no corresponding heat build-up. Thus, thepositive properties of a protective and nurturing action is combinedwith an unchanged perspiration.

Foam formulations known so far contain conventional tenside/emulsifiersthat serve for the stabilization of the emulsion and for the resultingfoam stability.

Conventional emulsifiers or tensides, respectively, are, however,repeatedly identified as causing irritations in the use of skin careproducts, such as e.g. a dysfunction of the skin barrier or Mallorcaacne.

Thus, there is a need of individual skin care compositions that arebetter adapted to the needs of the skin than conventional emulsionsystems on the basis of emulsifiers and, thus, provide a better skinprotection and a better skin care.

The use of cream bases having a lamellar structure based in itscomposition on the membrane-forming epidermal lipids in foamformulations so far has not been described.

It is the object of the present invention to provide improved foamformulations, particularly improved foam creams, avoiding theabove-mentioned disadvantages of formulations according to thestate-of-the-art.

SUMMARY OF THE INVENTION

The applicant has surprisingly found that emulsions comprising an oilphase and a water phase wherein the oil phase comprises at least onemembrane-forming substance forming a lamellar membrane in the foamformulation are suitable as basis for foam formulations. In a preferredembodiment, the foam formulations are substantially free of emulsifier,i.e. they substantially contain no conventional emulsifiers wherein thesubstance or the mixture of substances that leads to the formation of alamellar membrane is not considered a conventional emulsifier. Forexample, in the technical field it is, for example, acknowledged tocharacterize the commercial product Physiogel® cream containing DMS®concentrate as “emulsifier-free”.

Membrane-forming substances and mixtures of substances according to thepresent invention are typically non-soluble in water, while conventionalemulsifiers, especially tensides having a comparable HLB-value of about10 are as a rule soluble in water. Furthermore, the membrane-formingsubstances not soluble in water according to the present invention arenot capable of spontaneously emulsifying oils, while conventionalemulsifiers especially those having a high HLB-value are capable tospontaneously emulsify oils. Conventional emulsifiers having a lowHLB-value are not capable to form lamellar structures or liposomes alonein contrast to membrane-forming substances according to the presentinvention, e.g. phospholipids. A special feature of membrane-formingsubstances according to the present invention in contrast toconventional emulsifiers is that, for example, phospholipids have a HLBof 10, however, are not soluble in water.

Preferably the membrane-forming substances of the invention have aHLB-value of more than 8, more preferably of 9 to 11, and mostpreferably of 9.5 to 10.5.

According to the present invention the positive characteristics of foamformulations are combined with those of emulsions in which the oil phasecomprises at least one membrane-forming substance that forms a lamellarmembrane in the foam formulation. Thus, especially foam formulations canbe prepared combining the positive properties of the foam, namely thephysical structure and the convenient application, with a good skincompatibility. This property allows the use of foam formulations forcosmetic and dermatologic formulations to be employed in case ofsensitive types of skin. Thus, skin compatibility and convenience ofapplication is combined advantageously with each other. The lamellarstructure of the at least one membrane-forming substance that isimportant for the skin compatibility has not been considered in foamformulations of the state-of-the-art.

Nevertheless, it is not obligatory that such emulsions lead to stablefoam products upon foaming. Foams are obtained, as already mentioned,e.g. by incorporating propellants into O/W emulsion systems. In casethat the propellant dissolved in the dispersed oil phase evaporates uponfoaming, a foam is foamed (dispersion of gas in liquid). Foaming orexpanding, respectively, of the propellant dissolved in the dispersedoil phase leads to a dilatation of the dispersed oil phase. It now hasbeen surprisingly found that upon foaming of the inventive foamformulations breaking of the preparation does not occur and a suitablefoam is formed. The formed foam is stable enough in order to be, e.g.,applied to the skin.

The invention relates to foam formulations comprising an oil phase and awater phase, wherein the oil phase comprises at least onemembrane-forming substance that forms a lamellar membrane in the foamformulation.

Preferably, the invention relates to foam formulations on the basis ofnatural or skin-like ingredients, respectively, providing for a betterskin compatibility.

Furthermore, the invention relates to the use of foam formulations basedon emulsions as carriers for active agents, as skin care agent, as skincleaning agent or as sunscreen. The foam formulation, therefore, can beemployed as cosmetic, medical product or pharmaceutical composition.

Moreover, the invention comprises a method of manufacture of foamformulations based on emulsions in which the oil phase comprises amembrane-forming substance that forms a lamellar membrane in the foamformulation. The method comprises the steps:

-   -   a) Producing an emulsion preferably of the oil-in-water type,    -   b) Filling the emulsion and propellant into a pressurized        container, or    -   c) Filling the emulsion into a container other than a        pressurized container that upon dispensing of the emulsion        generates a foam.

DESCRIPTION OF THE DRAWINGS

FIGS. 1-3 show polarization microscopic photographs of the foamformulation of example 3.

FIG. 1 shows lamellar membrane-forming structures that can be recognizedby means of the so-called Maltese crosses (especially in the upper leftimage area).

In addition, in FIG. 2, the gas phase of the foam formulation can berecognized in the form of gas bubbles. Maltese crosses can be shownespecially in the boundary surface to the gas phase.

Moreover, in FIG. 3, Maltese crosses can be recognized in the boundarysurface to the gas bubbles of the foam.

DETAILED DESCRIPTION OF THE INVENTION

According to the present invention, foam formulations are formulations,especially emulsions, that are evidently adapted for the formation of afoam. In particular, the formulations may be either filled together witha propellant into a pressurized container or may be filled withoutpropellant into a container other than a pressurized container thatallows for the formation of a foam upon dispensing of theformulation/emulsion. For example, pump spray containers may be used.

In a preferred embodiment, the foam formulation is a foam cream.

According to the present invention, essentially emulsifier-freeemulsions are such emulsions that do not contain more than 1.5 weightpercent of conventional emulsifiers, preferably not more than 1,0%, morepreferably not more than 0,5%. According to the invention,emulsifier-free emulsions are such emulsions that do not containconventional emulsifiers.

According to the present invention, a membrane-forming substance forminga lamellar membrane is a substance that preferably has simultaneously ahydrophilic as well as a hydrophobic part of the molecule. Preferred aresubstances such as e.g. phospholipids, such as lecithins, sphingolipids,ceramides, cholesterol, fatty alcohols, fatty acids as well as mono-and/or diesters thereof, as well as sterols, etc. Triglycerides (nothydrophilic and lipophilic), squalene (not hydrophilic and lipophilic),squalane (not hydrophilic and lipophilic), may also be contained inmixtures of compounds comprising the membrane-forming substance.

Preferred membrane-forming substances are phospholipids, sphingolipids,ceramides, cholesterol, fatty alcohols, fatty acids as well as theirmono- and/or diesters, and sterols. Such substances or correspondingmixtures of substances can be dispersed in a suitable way with anaqueous phase under formation of lamellar membranes. This can beachieved, for example, by dispersing under high energy input (e.g. highpressure homogenization, ultrasound). In case of high pressurehomogenization, pressures in the range of 50.000-250.000 kilopascal(500-2500 bar) are employed in this respect, more preferably of100.000-150.000 kilopascal (1000-1500 bar). In other cases, a highenergy input for forming lamellar membrane structures is not compulsorynecessary (for example often in case of using non-hydrogenated lecithinshaving a low phase transition temperature in connection with suitablelipids, such as e.g. isopropyl myristate). The use of particularconcentrates forming a lamellar phase is also possible.

The presence of lamellar structures in the dispersion can easily bedetermined by a person skilled in the art by means of methods known inthe art. Suitable methods of measuring are, for example, described inClaus-Dieter Herzfeld et al. (editor), Grundlagen der Arzneiformlehre,Galenik 2, Springer Verlag, 1999. In this respect, the method ofpolarization microscopy is especially worth noticing. In this method,two polarization films in the so-called cross position in which theoscillation planes of the generated polarized light are perpendicular toeach other are placed above and below the object to be analyzed. Theoscillation plane of the irradiated light is changed by the sample sothat a fraction of the light can pass through the second polarizationfilm. The presence of lamellar phases can be recognized here typicallyby means of so-called Maltese crosses.

According to the present invention, a lamellar membrane is arranged suchthat it has a layered structure such that the upper layer of thesubstance is respectively directed to a lower layer of the substance.The direction of the individual substance layers occurs independently ofthe used solvent such that e.g. the hydrophilic parts of the substanceare directed outwards and the hydrophobic moieties are directed inwardsto each other, or vice versa.

In case that two layers of the substance are directed in theabove-described sense, the resulting structure is designated as a singlemembrane, while in case of arranging two further layers, this lamellarstructure is designated as a double membrane. According to the presentprinciple, still further layers may be associated to the (double)membrane already present resulting in a multiple membrane structure.According to the present invention, the membrane may be present as asingle membrane, as a double membrane or also as a multiple membrane.

A “wash-out” effect is understood as a decreasing of the moisture of theskin after completing an application of the skin care composition belowthe initial value.

According to the present invention, bioidentical fats are fats of plantorigin that occur in the body.

Oil Phase

Suitable components that may form the oil phase may be selected frompolar and unpolar lipids or mixtures thereof.

The oil phase of the inventive formulations is advantageously selectedfrom the group of phospholipids, such as lecithins, (mono-, di-, tri-)glycerides (especially triglycerides, such as e.g. fatty acidtriglycerides), sphingolipids, from the group of propylene glycol orbutylene glycol fatty acid esters, from the group of natural waxes ofanimal or plant origin, from the group of ester oils, from the group ofdialkyl ethers and dialkyl carbonates, from the group of branched andnon-branched hydrocarbons and waxes as well as from the group of cyclicand linear silicon oils.

Foam formulations according to the present invention allow for animproved skin care action of the formulation due to the lamellarmembrane structure and the resulting structural similarity to thestructure of intercellular lamellar lipid structure of epidermal lipds,especially the stratum corneum. Due to the analogous structure of thelamellar structure of the skin, integration of the membrane into theskin is facilitated. The integration leads also to an improvement,especially a stabilization and recovery of the skin barrier. An intactskin barrier protects the skin from too high a moisture loss. Animprovement of the skin barrier can also result in an improved smoothingof the skin and may decrease the “wash-out” effect, wherebyadvantageously an improved long-term effect is obtained in comparison toconventional foam formulations.

Preferred foam formulations of the present invention employ “skin-like”components, in order to obtain similarity of the lamellar membranepresent in the foam formulation with the skin. In this respect,especially preferred embodiments replace, e.g., the natural glyceridespresent in the sub-corneas layer (the skin predominantly contains amixture of di- and triglycerides) by, e.g., triglycerides (of plantorigin), squalene by, e.g. squalane, which is less sensitive tooxidation, ceramides by ceramide 3 (from yeast), cholesterol byphytosteroles (of plant origin) and phospholipids by phospholipids (ofplant origin).

In a preferred foam formulation of the invention, the membrane-formingsubstance comprises a lipid, more preferably a triglyceride and/orphospholipid. In an especially preferred foam formulation of theinvention, the triglyceride is caprylic acid/caprinic acid triglycerideand/or the phospholipid is hydrogenated lecithin.

In a further preferred foam formulation of the present invention, theformulation may further comprise lecithin, preferably hydrogenatedlecithin.

The preferred inventive foam formulations may further contain furthercomponents, such as e.g. stabilizers such as e.g. alcohols or glycols.Preferred are glycols, in particular propylene glycol, caprylyl glycolor mixtures thereof.

In preferred foam formulations of the invention, further components maybe comprised such as e.g. butyrospermum parkii (shea butter), squalane,glycerides, ceramides, preferably ceramide 3, or mixtures thereof.

A preferred foam formulation of the invention comprises a substantiallyemulsifier-free emulsion. An especially preferred foam formulation ofthe invention is free of emulsifier. In a particularly preferredembodiment, the foam formulation is free from water-soluble conventionalemulsifiers having a HLB-value of about 10. In a preferred embodiment,the formulation is especially free from the following compounds:

Carboxylates, such as e.g. sodium stearate, aluminium stearate;

sulphates, such as e.g. Na-dodecyl sulphate, Na-cetyl stearyl sulphate,Na-laurylether sulphate;

Sulphonate: Na-dioctylsulphosuccinate;

Quaternary ammonium compounds, such as e.g. cetyl trimethyl ammoniumbromide, benzalconium bromide;Pyridinium compounds, such as e.g. cetyl pyridinium chloride;Betains, such as e.g. betain monohydrate;Macrogol fatty acid esters, such as e.g. macrogol-30-stearat;Glycerol fatty acid esters, such as e.g. glycerol monostearate, glycerolmonooleat, glycerol monoisostearate, partial glycerides, polyoxyethylenesorbitan fatty esters of medium chain length, such as e.g. Tween®,polyoxyethylene-(20)-sorbitan monostearat;Sorbitan fatty acid esters, such as e.g. sorbitan laurat, sorbitanmonooleat, sorbitan monopalmitate, sorbitan monostearate, sorbitantristearate, sorbitan sesquioleat;Sucrose fatty acid esters, such as e.g. sucrose monostearate, sucrosedistearate, sucrose cocoate;Macrogol fatty alcohol ethers, such as e.g. Cetomacrogol 1000, macrogolcetostearylether, macrogol oleylether, Lauromacrogol 400;Stearin alcohols, such as e.g. cholesterol, lanolin, acetylated lanolin,hydrogenated lanolin, lanolin alcohols;macrogol glycerol fatty acid esters, such as e.g.macrogol-1000-glycerol-monooleat, Macrogol-1000-glycerol-monostearat,macrogol-1500-glycerol, triricinoleat, macrogol-300-glycerol-(hydroxylstearat), macrogol-5-glycerol-stearat, macrogol glycerol hydroxystearat;Polyglyercol fatty acid ester, such as e.g. triglycerol diisostearat.

In the present invention, the oil phase comprising a suitable substanceor such a mixture of substances for forming the lamellar membrane isdispersed with a water phase under conditions that result in theformation of a lamellar phase. If necessary, this is done, for example,by dispersing under high energy input, such as e.g. by ultrasound or bymeans of high pressure homogenization, wherein pressures of about 50.000to about 250.000 kilopascal (about 500 to about 2500 bar), preferablyabout 100.000 to about 150.000 kilopascal (about 1000 to about 1500 bar)are used. In other cases, especially when using non-hydrogenatedlecithin having a low phase transition temperature as themembrane-forming substance, simple dispersing is often alreadysufficient without the additional need of high energy input. Thepresence of a lamellar phase can, as mentioned above, easily bedetermined by a person skilled in the art using methods known in the artsuch as e.g. polarization microscopy.

In an especially preferred embodiment, the membrane-forming substancecomprises a phospholipid, such as e.g. lecithin or hydrogenatedlecithin, and additionally a lipid. More preferably, the phospholipid isa mixture of lecithin and hydrogenated lecithin. In an especiallypreferred embodiment, the weight ratio of lecithin to hydrogenatedlecithin is about 10:1 to about 1:10, more preferably about 5:1 to about1:5 and still more preferably the ratio of lecithin to hydrogenatedlecithin is about 1:1. The lipid present in addition to phospholipidcomprises in a preferred embodiment a liquid wax ester, such as e.g.isopropyl myristate, -palmitat, stearat or the like. Furthermore,further optional lipids, such as e.g. peanut oil or triglycerides ofmedium chain length (preferably C₈-C₁₂ triglycerides), may be present inaddition to wax ester. The weight ratio of total phospholipid (e.g.lecithin+hydrogenated lecithin) to total lipid (e.g. wax ester+optionaltriglycerides) is in this embodiment preferably about 1:5 to about 1:1,preferably about 1:2.

The mixture of phospholipid and lipid is, for example, dispersed as amelt with water under high energy input. The high energy input can beeffected by means of ultrasound or by means of high pressurehomogenization, wherein pressures of 50.000 to 250.000 kilopascal (500to 2500 bar) are employed, preferably 100.000 to 150.000 kilopascal(1000 to 1500 bar). In the water phase, further additives may optionallybe present as described in the present specification, such as e.g.glycerol or thickening agent (e.g. xanthan gum and/orhydroxypropylmethyl cellulose (hypromellose)).

Further optional ingredients are described below in connection with DMS®compositions. In particular, the obtained formulation may besubstantially emulsifier-free, preferably free of emulsifier, i.e. inthe formulation, substantially no or no, respectively, conventionalemulsifier is present, wherein the membrane-forming substance or themembrane-forming mixture of substances is not considered a conventionalemulsifier. Upon dispersing this mixture in the described manner, adispersion is obtained that is suitable for forming a foam formulation(e.g. by using propellants or a pump spray) and further for forming alamellar membrane.

Further cream bases based on the above-described “skin-like” componentsare also known in the art as DMS® cream bases.

The DMS® base compositions can have the following components: caprylicacid/caprinic acid triglyceride, shea butter, squalane, ceramide 3,hydrogenated lecithin, palm glycerides, persea gratissima, palm oil(elaesis guineensis).

As stabilizers in the DMS® compositions may be used e.g. alcohols orglycols such as e.g. pentylene glyclol, caprylyl glycol or mixturesthereof.

A commercially obtainable DMS® base comprises caprylic acid/caprinicacid triglyceride, shea butter, squalane, ceramide 3, hydrogenatedlecithin as well as pentylene glycol.

A further commercially obtainable DMS® base comprises caprylicacid/caprinic acid triglyceride, shea butter, squalane, ceramide 3,hydrogenated lecithin as well as alcohol.

A further commercially available DMS® base comprises caprylicacid/caprinic acid triglyceride, shea butter, squalane, ceramide 3,hydrogenated lecithin, persea gratissima as well as caprylyl glycol.

A further commercially available DMS® base comprises caprylicacid/caprinic acid triglyceride, shea butter, squalane, ceramide 3,hydrogenated lecithin, palm glycerides, elaesis guineensis as well aspentylene glycol.

A preferred DMS® base comprises caprylic acid/caprinic acidtriglyceride, butyrospermum parkii, squalane, ceramide 3, hydrogenatedlecithin, as well as pentylene glycol.

An especially preferred caprylic acid/caprinic acid triglyceride isobtainable under the designation Miglyol 812 of the company Sasol andmixtures thereof with further oil and wax components.

In addition, especially preferred is the caprylic acid/caprinic acidtriglyceride obtainable under the designation Miglyol 812 of the companySasol/Myritol 312 of the company Cognis.

The inventive emulsions preferably contain from about 5 to 50 weightpercent oil phase, especially preferably 10 to 35 weight percent andmore preferably 15 to 35 weight percent oil phase. The data respectivelyrefers to the total weight of the emulsion without propellant.

These cream compositions are in particular used in case of irritated,dry up to very dry, sensitive up to very sensitive, allergic and eczemicskin.

In addition, the oil phase preferably may contain further components,such as e.g. fatty acids, in particular stearinic acid, or oils, such ase.g. Cetiol V.

In the DMS concentrates and the inventive formulations, furtherconventional adjuvants (not bioidentical) such as fragrances, colorants,comedogene lipids (e.g. mineral oils) and physiologic emulsifiers arepreferably omitted, since these components are potentially sensitizingand may lead to irritations of the skin.

Aqueous Phase:

The aqueous phase can contain cosmetic adjuvants, e.g. lower alcohols(e.g. ethanol, isopropanol), lower dioles or polyoles as well as ethersthereof (e.g. propylene glycol, glycerole, butylene glycol, hexyleneglycol and ethylene glycol), foam stabilizers and thickening agents.

Suitable thickening agents are polymeric thickening agents that arepartly soluble in water or are at least dispersible in water and form inaqueous systems gels or viscous solutions. They increase the viscosityof the water in that they either bind water molecules (hydratation) or,on the other hand, include and encapsulate the water into theirintertwined macromolecules wherein movability of the water is decreased.Suitable polymers are:

-   -   modified natural materials, such as cellulose ether (e.g.        hydroxypropyl cellulose ether, hydroxyethyl cellulose and        hydroxypropylmethyl cellulose ether);    -   natural compounds, such as e.g. agar-agar, carrageen, polyoses,        starch, dextrins, gelatine, casein;    -   synthetic compounds, such as e.g. vinyl polymers, polyether,        polyimines, polyamides and derivates of polyacrylic acid; and    -   inorganic compounds, such as e.g. polysilicic acid and clay        minerals.

Preferably, a cellulose ether is contained as thickering agent in theformulation of the invention. Hydroxypropylmethyl cellulose isespecially preferred. A hydroxypropylmethyl cellulose especiallypreferred according to the invention is Metolose 90S H100. The generaldesignation in the art for Hydroxypropylmethyl cellulose ishypromellose.

A further preferred thickening agent is xanthan gum, especiallyKeltrol®CG xanthan gum.

Hydroxypropylmethyl cellulose and xanthan gum can be employed in theinventive formulations also simultaneously.

The inventive emulsions preferably contain from 0.2 to 3.0 weightpercent thickening agent (based on the dry weight of the thickeningagent and the total weight of the emulsion without propellant).Especially preferred are 0.5 to 2.5 weight percent thickening agent.

Active Agents:

The contained active agent may be selected from all active agents andmixtures thereof that can be applied to the surface of the skin. Theactive agent can act cosmetically or pharmaceutically. Accordingly,cosmetic or dermatologic (to be employed as medical product orpharmaceutical composition) foam formulations are obtained. Furthermore,the formulation may be employed for protecting the skin againstenvironmental influences. The active agent can be completely of plantorigin or can be synthetic. The group of active agents may overlap withother groups of ingredients, such as e.g. the oil component, thethickening agents or the solid emulsifiers. For example, some oilcomponents also may act as active agents, such as e.g. oils havingpolyunsaturated fatty acids or solid emulsifiers, such as e.g.particulate titanium dioxide that may serve as UV-filter. Depending onthe characteristics, the substances are to be classified into severalgroups.

Active agents of the inventive formulations are advantageously selectedfrom the group of substances having moisturizing and barrierstrengthening properties, such as e.g. hydroviton, an emulation of NMF,pyrrolidone carbonic acid and salts thereof, lactic acid and saltsthereof, glycerol, sorbitol, propylene glycol and urea, substances ofthe group of proteins and protein hydrolysates, such as e.g. collagen,elastin as well as silk protein, substances of the group of glycoseaminoglucanes, such as e.g. hyaluronic acid, of the group ofcarbohydrates, such as e.g. pentavitin that corresponds in itscomposition to the carbohydrate mixture of the human sub-corneous layerand the group of lipids and lipid precursors such as for exampleceramides. Further advantageous active agents in the sense of thepresent invention may be selected from the group of vitamins, such ase.g. panthenol, niacin, α-tocopherol and its esters, vitamin A as wellas vitamin C. Moreover, active agents selected from the group ofantioxidants e.g. galates and polyphenoles may be used. Urea, hyaluronicacid and pentavitin are preferred substances.

It is further preferred that substances having skin soothing andregenerative action are employed as active agents, such as e.g.panthenol, bisabolol and phytosteroles.

Advantageous active agents in the sense of the present invention arealso plants and plant extracts. These are e.g. algae, aloe, arnica,barber's rash, comfrey, birch, nettle, calendula, oak, ivy, witch hazel,henna, hop, camomile, ruscus, peppermint, marigold, rosemary, sage,green tea, tea tree, horsetail, thyme and walnut as well as extractsthereof.

The inventive formulations may further contain as active agentsantimycotics and antiseptics/disinfectants of synthetic or naturalorigin.

Further active agents are glycocorticoides, antibiotics, analgetics,antiphlogistics, antirheumatics, antiallergics, antiparasitics,antipruriginosics, antipsoriatics, retinoids, local anaesthetics,therapeutic agents for veins, ceratolytics, hyperemic substances,coronary therapeutic agents (nitrates/nitro-compounds), virus statics,cytostatics, hormones, agents promoting wound healing, e.g. growthfactors, enzyme preparations and insecticides.

Further Components of the Emulsion:

The formulations may optionally further contain colouring agents,pearlescent pigments, fragrances/perfumes, sunscreen filter substances,preservatives, complex formers, antioxidants and repellent agents, aswell as pH-value regulating agents.

However, in a preferred embodiment, formulations of the invention arefree from components that may lead to irritations of the skin, inparticular are free from fragrances, perfume, colorants and conventionalemulsifiers.

The inventive foam formulations may contain apart from the componentsalready described above further natural fats such as e.g. shea butter,neutral oils, olive oil, squalane, ceramides and moisturizing substancesas usual in the art.

The above list of individual components of the emulsion should beconsidered such that individual exemplified components may be classifiedinto several groups because of its different properties.

Propellants:

Suitable propellants are e.g. N₂O, propane, butane and i-butane. Thecompleted foam formulation contains 5 to 15 weight percent ofpropellant, preferably about 10 weight percent.

Method of Manufacture

The foam formulations according to the invention are prepared byproviding an emulsion, preferably of the oil-in-water type and fillingthe emulsion and optionally propellant into a suitable container such ase.g. a pressurized container. As an alternative to propellant andpressurized container, the emulsion may also be filled into a differentcontainer that is suitable to dispense the emulsion as a foam even inthe absence of propellant. Such systems are known to a person skilled inthe art.

In particular, the inventive emulsions are prepared by means of a methodcomprising the following steps:

-   -   (1) Providing an oil phase optionally comprising at least one        membrane-forming substance forming a lamellar membrane in the        formulation,    -   (2) Providing an aqueous phase,    -   (3) Combining and homogenizing of both phases, for example, by        means of ultrasound or high pressure homogenization,    -   (4) Optionally adding at least one or at least one further        membrane-forming substance,    -   (5) Optionally homogenizing, for example, by means of ultrasound        or high pressure homogenization in order to obtain an emulsion,        wherein in at least one of the steps (1) or (4) at least one        membrane-forming substance is included that forms in the        formulation a lamellar membrane.

Preferably, the oil phase and the aqueous phase are each mixed at atemperature in the range of from about 40 to 90° C. and are homogenized;a temperature range of from about 60 to about 80° C. is especiallypreferred, more preferably a temperature of about 70° C.

For homogenizing, every means or method known in the art can be used.Preferably, the phases are homogenized using a high-speed stirringdevice. In a preferred embodiment, homogenizing is carried out by meansof high pressure homogenization. In a further preferred embodiment,homogenizing is carried out by means of ultrasound.

In a preferred production method, the oil phase is mixed into theaqueous phase and is homogenized. If necessary, the emulsion is cooleddown to room temperature under stirring. In an especially preferredmethod, a suitable amount of a DMS® concentrate is added to this mixtureand the concentrate is incorporated into the present emulsion. Themethod that is described in the following can also be carried out withother lamellar phases instead of DMS® concentrate.

The DMS® concentrate can already be added to the oil phase beforehomogenizing with the aqueous phase or can be added to the mixture ofthe homogenizing the oil and aqueous phase. It is preferred that theDMS® concentrate is added to the mixture after the first homogenizingstep and the mixture is then homogenized.

In case the emulsion comprises a thickening agent, the methodadvantageously comprises the following further steps:

-   -   (6) Providing an aqueous solution of thickening agent,    -   (7) Mixing the solution of thickening agent with the emulsion.

Preferably, the inventive emulsion is loaded with about 10 weightpercent of propellant.

Applications

The foam formulations of the present invention can be employed for allcosmetic and dermatologic (as a medical product or pharmaceuticalcomposition) purposes. For example, the formulations may be employed asskin care agent or skin cleaning agent. Furthermore, they may be used ascarriers for active agents and may be employed in the medicaldermatologic field. In particular, the formulations may be employed assunscreen.

EXAMPLES Composition of the Foam Formulation

a) Aqueous Phase

The aqueous phase is provided by mixing the components.

Component Amount HPMC (Metolose 90SH100) 1.5 g Xanthan gum (Keltrol ®CG) 0.5 g Water  78 g

b) Oil Phase

Example 1

Component Example 1 DMS Concentrate  5 g Miglyol 812 14 g Stearinic acid 1 g Aqueous phase ad 100 g

Example 2

Component Example 2 DMS Concentrate  5 g Miglyol 812 14 g Stearinic acid 1 g Cetiol V  5 g Aqueous phase ad 100 g

Stearinic acid is dissolved under heating up to about 70° C. in Miglyol812 (Example 1) or in the mixture of Miglyol 812 and Cetiol V (Example2), respectively.

This oil phase is added into the aqueous phase under stirring and ishomogenized using a high-speed stirring device. The resulting emulsionis cooled down to room temperature under stirring and the DMS®concentrate is incorporated by means of a high-speed stirring device.

The used DMS® concentrate has the following INCI components:

Aqua (and) Hydrogenated Lecithin (and) Caprylic/Capric Triglyceride(and) Pentylene Glycol (and) Butyrospermum Parkii (and) Glycerin (and)Squalanee (and) Ceramide 3

Manufacture of the Foam Formulation

90 g of the emulsion prepared as above are filled into an aerosolcontainer and are loaded after closing with a valve cap with 10 gpropellant.

Example 3

Component Example 3 soya lecithin  3.0 g hydrogenated soya lecithin  3.0g triglycerides of  7.0 g medium chain length isopropyl myristate  7.0 gxanthan gum  0.4 g hypromellose  1.2 g glycerol 85%  5.0 g water 73.4 g

Manufacture

The mixture of soya lecithin and hydrogenated soya lecithin (e.g.Phospholipon 80 H and phospholipon 85 G) is dissolved in a mixture oftriglycerides of medium chain length (e.g. Miglyol 812) and isopropylmyristate at 60° C. Under high energy input (e.g. ultrasound or highpressure homogenization), the lipid melt is dispersed in a mixture ofwater and glycerol (high pressure homogenizer: Avestin Emulsiflex-C3;pressure: 1400 bar). Subsequently, the solution of xanthan gum (e.g.Keltrol CG) and hypromellose (e.g. Metolose 90SH100) in water is addedunder stirring.

Manufacture of the Foam Formulation

90 g of the membrane-forming emulsion as prepared above are filled intoan aerosol container and is loaded with 10 g propellant after closingwith a valve cap.

Foam Formation

A stable cream-like foam having fine bubbles is formed upon dispensingthe foam formulation from the pressurized container by means of asuitable valve having a foam applicator attached. The structure of thecream-like foam is maintained for a duration that is sufficient foruniformly dispersing the foam on the skin.

1. A foam formulation comprising an emulsion which comprises an oilphase and a water phase, wherein the oil phase comprises at least onemembrane-forming substance forming a lamellar membrane in the foamformulation.
 2. The foam formulation according to claim 1, wherein theemulsion is an oil-in-water type emulsion.
 3. The foam formulationaccording to claim 1, wherein the at least one membrane-formingsubstance comprises a lipid.
 4. The foam formulation according to claim3, wherein said lipid is a triglyceride that comprises caprylicacid/caprinic acid triglyceride.
 5. The foam formulation according toclaim 3, wherein the lipid comprises a phospholipid.
 6. The foamformulation according to claim 5, wherein said phospholipid is lecithinor lecithin that comprises hydrated lecithin.
 7. The foam formulationaccording to claim 1, wherein the emulsion further comprises at leastone thickening agent which is preferably selected from the groupconsisting of hydroxypropylmethyl cellulose, xanthan gum and mixturesthereof.
 8. The foam formulation according to claim 1, wherein theemulsion further comprises a stablilizer.
 9. The foam formulationaccording to claim 8, wherein the stabilize comprises pentylene glycol.10. The foam formulation according to claim 1, wherein the emulsionfurther comprises shea butter, glycerol, squalan, ceramide, preferablyceramide 3 or mixtures thereof.
 11. The foam formulation according toclaim 1, wherein the emulsion further comprises an oil or Oilslubricating substance.
 12. The foam formulation according to claim 1,wherein the emulsion further comprises at least one active agent. 13.The foam formulation according to claim 12, wherein the active agent isselected from the group consisting of hydroviton, pyrrolidone carbonicacid and salts thereof, lactic acid and salts thereof, glycerol,sorbitol, propylene glycol, urea, collagen, elastin, silk protein,hyaluronic acid, pentavitin, ceramides, panthenol, niacin, a-tocopheroland esters thereof, vitamin A, vitamin C, galates, polyphenols,panthenol, bisabolol, phytosteroles, glycocorticoides, antibiotics,analgetics, antiphlogistics, antirheumatics, antiallergics,antiparasitatics, antipruriginosics, antipsoriatics, retinoids, localanaesthetics, therapeutic agents for the veins, ceratolytics,hyperemisic compounds, coronary therapeutics (nitrates/nitro-compounds),virus statics, cytostatics, hormones, agents promoting wound healing,growth factors, enzyme preparations, insecticides and plant materialsuch as e.g. plant extracts of algae, aloe, amica, barber's rash,comfrey, birch, stinging nettle, calendula, oak, ivy, witch hazel,henna, hops, camomile, ruscus, peppermint, marigold, rosemary, sage,green tea, tea tree, horsetail, thyme walnut and mixtures thereof. 14.The foam formulation according to claim 1, wherein the emulsion is asubstantially emulsifier-free emulsion.
 15. The foam formulationaccording to claim 1, wherein the emulsion is free of emulsifier. 16.The foam formulation according to claim 3, wherein the lipid comprisesbioidentical fats.
 17. The foam formulation according to claim 1,wherein the formulation is a foam cream.
 18. The foam formulationaccording to claim 1, wherein the emulsion comprises at least onephospholipid and at least one liquid wax ester.
 19. The foam formulationaccording to claim 18, wherein the phospholipid comprises lecithin, or atriglyceride.
 20. The foam formulation according to claim 1, wherein themembrane-forming substance is not soluble in water. 21.-33. (canceled)